function() does not exist error with 4.1b3

I have a large application that works OK under 4.1b2 with minor issues.

However under 4.1b3 I start to see errors indicating that functions defined in my
own classes dont exist.

I have several classes which are created with Ext.define('') but are not derived from
any other class. These are generally functional classes which are used in the application.

I have a config: defined and a constructor which calls initConfig().

This all works fine in Ext 4.0 and up to 4.1b2 but suddenly fails in 4.1b3. Looking with
firebug, I notice that some of the functions defined in the class look like they havent
been properly defined in the class. They appear as 'function()' but there is no info.

Other functions have a + which I can click on which give information on the function
name, etc.

I also see a lot of new booleans _isBlahInitialized for variables 'Blah' that I've put in
config.